Check Engine Flash?

[04MaroonTB]

I have been noticing sometimes that my Check Engine Light will flash real quick on and off. For awhile I just thought it was sun glare that would hit area but when it was dusk yesterday and I noticed it happen. I can't tell how frequently it happens or when exactly.
Has anyone ever had this happen before? If I take it to the dealer and they hook it up nothing will show up so I was wondering if I could check somethings before making an issue out of it.

[MoJoe]

The only thing I could think of making it flash other than an error would be a short to that bulb possibly? Start with the dealer though like you said. :m2:

[texas arsenal]

Did you just fuel up? Check your gas cap. A flashing SES light could be an indication of the gas cap not being sealed properly.

[04MaroonTB]

Thanks. I will check that out. I have heard dealers charge for a diagnostic test and all they did was tighten the gas cap.

[ParadoxJr]

Shouldn't be charging, unless you are out of the Warranty Period.

Russ

[Sinecure]

Don't the TBs, Envoys, etc. have a separate light for tightening your gas cap? At least my TB does. Maybe it was just added in recent years.

[deathbynosleep]

I have been noticing sometimes that my Check Engine Light will flash real quick on and off. For awhile I just thought it was sun glare that would hit area but when it was dusk yesterday and I noticed it happen. I can't tell how frequently it happens or when exactly.
Has anyone ever had this happen before? If I take it to the dealer and they hook it up nothing will show up so I was wondering if I could check somethings before making an issue out of it.

I have the same problem in my 04. It seems like once a week it flashes on and off. It's so fast i thought i was going crazy at first. Then i actually started going crazy cause i know it came on but i didn;t have time to read what light was coming on. I haven't taken it to the dealer yet. I also have a problem with my voltage constantly dropping to like 10 then going back up to 14.

[Jman423]

.......I also have a problem with my voltage constantly dropping to like 10 then going back up to 14.
Uh oh, I hope you are still under waranty... That sounds like an alternator or component. :m2:

[deathbynosleep]

Uh oh, I hope you are still under waranty... That sounds like an alternator or component. :m2:

Yeah it's still under warranty for another 2 years. Could be the Alternator. I've already had my battery die, then recharged, then die a week later, then i had a friend take one out of a new TB. So i have a brand new battery.

[02EnvoySLE Guy]

Yeah it's still under warranty for another 2 years. Could be the Alternator. I've already had my battery die, then recharged, then die a week later, then i had a friend take one out of a new TB. So i have a brand new battery.

Could've been a bad cell in your old battery as well. Keep an eye on it and if it keeps acting up, head to autozone and get a charging system stress test done :m2:

They will do the job for free.

[Laloosh]

I think i read in the manual that a flashing engine light is very bad, i would go get that checked out right away. If you have onstar, hit your little onstar button and see if they come up wiht anything, or maybe try going to autozone to see if any codes pop up, if all else fails, its stealership time

[jallshouse]

just had an experiance that may help you. i picked up my TB on thursday from my dealer after some warenty work, after i drove away i noticed my check engine light was on (solid) i called right away from my cell becuase i didnt undetstand why it was on when alls they were doing is installing my gas pedal, putting new wheels on, and replacing a door panel. i told the tech what was going on and he was like " we couldnt have done anything, we didnt touch anything in the engine compartment" but he told me to take the gas cap off and back on and drive for ten miles, if its still on bring it back in. i did what he said and it wasnt on the next time i started it. he also said if an engine light is on "solid" its not serious, but if its "blinking" DO NOT DRIVE IT, just park it and call them right away. now remember this is the same guy that started denying that they could not have done anything to make the light come on. i would recomend getting it to a dealer right away though, dont want something to happen to your ride

[deathbynosleep]

it's not a constant flashing though. It's like and on and off one time quicker than you can even look down and read it. If you were to be looking out the window you wouldn't even notice it. I plan on taking my car in still to have it looked at.

[jallshouse]

i noticed that after i replied, and then reread it :duh: it still wouldnt be a bad idea to take it in for a checkup

[ds8]

I have an '04 envoy with the same problem. Once a week or so the SES light flashes. OnStar cannot find an error code, nor can the dealership. They thought it might be a bad ignition switch so it was replaced, but did not help the problem. It is not an engine misfire or loose gas cap. Does anyone have a solution for this problem?

Thank you.

[ScarabEpic22]

Welcome to the site!:D

[regularjoe]

did anyone find a solution to this problem. i did a forum search and found this thread because my 04 tb is doing the same thing the ses light flashes every now and again once so fast you can just notice it. i does it once every week or so. any help would be appreciated thanks.

[6V92TA]

mines has only flashed once. At one time,it actually came on one day,stayed on for a few hours then went off like nothin never happened. That was 2 weeks ago....it hasnt done it since. Now the security light has flashed on and off a few times and doing this,the engine actually shudders like it wants to shut down. it's a very quick shudder and only happens when the security light flashes. Farther than that,nothin else happens. could it be a minor error or electrical fault?

[vball61]

Interesting that every poster complaining about intermittent flashing of this indicator owns an '04...

The MIL (malfunction indicator lamp, aka service engine soon light) is the only indicator in the cluster which is NOT commanded on through cluster logic or serial data. Instead, the engine control module (ECM) grounds a circuit from the cluster to turn the MIL indicator on. An intermittent short to ground of that wire could cause the flashing you're describing.

The circuit in question is a small BROWN/WHITE wire connected to pin B4 of the cluster connector.
On the 4.2L ECM, it's at pin 7 of the blue connector.
On Trailvoys with the 5.3L engine it's at pin 46 of the green ECM connector, and on those vehicles the circuit also passes through cavity C5 of the engine harness-to-IP harness inline 38-way connector located on the back side of the underhood fuse block.

[MTPockets]

A more advanced code scanner will tell if you if you have pending codes. Those are codes that have not yet set a solid SES light. An on/off-on/off *flashing* SES light means a misfire. Unfortunately, if you don't have any stored, pending codes, this will be almost impossible to diagnose, unless that particular service dept ran across that exact problem before and fixed it.

Joel

[BUC NASTY]

when i installed the LED bar on the rear bumper cover they check light keeps poping off and on all the time

[Envoyguy05]

I had an 04 Envoy with the flashing on and of check engine light . Ran fine . Also had the volatge drop and surge it will go away after you re-start

[Jozuah]

ok everyone that has an 04 READ THIS and check it, SAME problem here and i have an 04. but since the tune/latest calibration its GONE!

If the 11th digit of the VIN is a 2 and the last 8 of the VIN is less than 52114278 or if the 11th digit of the VIN is a 6 and the last 8 of the VIN is less than 56105324, reprogram the PCM with the latest calibrations. An updated engine calibration has been released to address this issue (intermittent stall or near stall during low speed deceleration)

this is a growing issue on 04's get a tune or get the calibration from GM but get it done today , even the latest calibration is like a tune compared with the crap buggy calibration that GM put on the effected model years.
this comes from actual experience on my 2004 TB I-6 with an effected VIN